Some of image forming apparatuses such as electrophotographic printers employ an optical printer head in which a plurality of light emitting elements are arranged as exposure means.
The image forming apparatuses equipped with the optical printer head are adapted to cause the light emitting elements to selectively emit light based on image data, and the light is irradiated through a lens array of the optical printer head to a photoreceptor. An electrostatic latent image is formed onto the surface of the photoreceptor by the light irradiation. The electrostatic latent image formed onto the photoreceptor is changed into a toner image through the process of development using toner, and the like. Then, an image is recorded by transferring and fixing the toner image onto a recording paper.
As the above optical printer head, those in which a plurality of light emitting element array units mounting a plurality of light emitting elements on a circuit board are arranged along a main scanning direction, and the adjacent light emitting element array units are arranged in a zigzag pattern by shifting them in a vertical-scanning direction have been proposed (for example, refer to patent documents 1 and 2).
Patent document 1: Japanese Unexamined Patent Application Publication No. 7-61035
Patent document 2: Japanese Unexamined Patent Application Publication No. 2001-328292